In order to help ensure that this web analysis page remains available, we
would greatly appreciate feedback on its use, particularily in the
clasroom, for presentations or for research. Mail to Cathy Smith at (cathy.smith@noaa.gov).

Page will plot maps or vertical crossections of selected variables. Select desired options and hit "create plot". Most
options have a default setting so a selection is not required. Default for year is last year and month available for dataset. You can select one or more years to composite, the season, the type
of statistic plotted (mean, anomaly, climatology), variable, level, map color, map location or bounds for vertical composites and
contour interval/range. If you have problems, please email with ALL the options you chose.

Please read ALL the instructions. Failure to do so may lead to misinterpretation of results.

Data is available from Jan 1948 to the present for most
variables and is updated the first or 2nd week of the month with
the previous month's data.
ONLY pressure and air temperature are available for the tropopause level
and ONLY u and v winds, relative humidity and pressure for the
surface. Streamfunction, divergence, vorticity and velocity
potential are available ONLY on sigma levels.
Vector winds: magnitude of winds are contoured. Arrows
show direction.
Sea Surface Temperature: This is from the NOAA OI SST data
(prescribed). Over land it is the skin temperature (prescribed as
well). Sea Ice (which varies near land) affects these values and so
the plotting range may not be as great over the tropics as desired.
Using a lower latitude may help with the plot.

Enter each year in a separate box. The year should correspond to the last
month of a season. Years should be w/i the range of the dataset you select. You can
subtract one set of years from another by entering a negative year.

Ftp to ftp.cdc.noaa.gov as anonymous. Please deposit your time series in /Public/incoming/timeseries using a unique name. Type in full pathname
(/Public/incoming/timeseries/yourfilename where requested.

You may select a time series or enter one yourself. Details on the supplied ones are at
Climate Index Web Page for
a complete reference for the included time series. Credit, proper references and definitions are provided. Please
read before using a particular time series or you may misinterpret what you are seeing. You can use the webpage
http://www.esrl.noaa.gov/psd/data/timeseries/
to create your own from monthly mean datasets. For ENSO years, see the PSD's ENSO FAQ.

To use you own or one obtained from the /Timeseries/ webpage, ftp to ftp.cdc.noaa.gov as anonymous. Place time series in /Public/timeseries using a unique name.
Check the "list of years" box and those years will be used. To use a time series, ftp a file to the same directory
as above. However, the format is

The missing value is mandatory and cannot be in the range of the data (-9999 is a good one).
Select "custom" time series.

For either a supplied time series or your own, you can composite off the actual values, anomalies (mean is based on the complete
range of years of the time series you submit or use, standardized anomalies (anomalies divided by the standard deviation),
or the percentile (0 to 100). Years used for composites are the subset of those years which match the criteria AND
are in the dataset you choose. For example, if you choose a Nino3.4 time series that has values greater than 1.5 sigma
and the dataset you are looking at goes to 1995, you will NOT get 1998 even if the Nino3.4 value is greater than 1.5 sigma.

Note that there are 6 years returned (using 1948-Nov 2013 data): 1961, 1964, 1970, 1977, 1983, 2003 The typical 3 center pattern
over North America clear is visible. Now, try years less than or equal to -1.25 sigma.
Only 5 years are returned: 1952,1956,1957,1969, 1972,1979 and the plot is somewhat opposite in pattern. You results may vary as more years are added to the PNA and the NCEP data.

Selecting a nonzero value for this will allow you to do a lagged composite. The years are determined from
one of the year entry methods above. Then, a composite is made N months before the dates you selected (-N) or after
the dates you selected (N). If lagging results in a date that is not in the range of the dataset, that date is not used.
As an example, select January 500 geopotential height for the PNA values greater than 1.25sigma. If you choose lag =-1, you will get 5 years:
1977,1981,1985,1992. A negative lag of one month will composite geopotential height for Dec 1976,1980,1984,1991. A positive lag
of 3 months will composite for April of 1976,1980,1984,1991. All lags are specified in months!. Please do lags only on positive years.

The composite represents the average of the variable for all months and years
entered. Composites can be created for one set of years minus another.
The years are normalized as in the following example: a set of 5 years minus a set of 2...

(1980+1981+1982+1983+1984)-(1985+1986)

will be calculated as

(1980+1981+1982+1983+1984)/5.-(1985+1986)/2.

Where each year represents a monthly/seasonal value.
There is currently no data before 1948 for reanalysis so, for
example, the season DJF 1948 contains Dec 1947 and therefore will
not be calculated. Likewise, seasons that would have years after the end of a dataset
will not be calculated. Missing values will not be used for data outside the time range of the dataset.

To rotate map, choose "custom" map projection and then
choose either northern or southern polar stereographic projection.
For lat range, enter 0 to 90 (for northern hemisphere) or -90 to 0
for southern. For longitude, the center of the longitude range
input will be at the bottom of the plot. To center along 0E,
choose -180 to 180, for example. To center at 90E, choose -90 to
270. You can plot sectors as well. The longitudes -90 to 90 in the
NH will plot the half hemisphere from the US across the Atlantic to
Europe.

Plots are based on 1981-2010 climatologies for NCEP Reanalysis data. Some other datasets have different climatology time periods.
Choose season; years are not needed. If years are entered, they are ignored.

Anomaly

Plots are of mean-climatology for each season/month. Climatology time period is generally
on 1981-2010 though some datasets have a different climatology period. For SST data from the reanalysis, anomalies
can be large in the mid to upper latitudes as sea ice influences the data. Hence, you may need to restrict the
range that is plotted.

A desired contour interval and range can be input
instead of the default being used. Different plots can be easily
compared (and the resulting gifs could be animated). For this
option to work, the interval AND the range must be input. There
must be at least 2 and less than 33 contours. The contour interval
must be positive and the range must go from low to
high.

Maps
To plot over the dateline, use values from 0 to 720. For example,
to plot 180W eastward to 180W, use 180 to 540. Be sure that the
western most longitude is less than the eastern., For example, to
plot 100W to 70W, use -100 to -70 or 260 to 290 and NOT 100 to
70.
There are 6 custom projections:

Height by latitude or longitude crossections
You can also plot crossections of data Latitude by Height.
Choose latitude/height or longitude /height for map type.
Chose longitudes to be averaged over and latitude range to be
displayed. Also choose level range. Only variables available at different
levels can be plotted this way: (geopotential height, air temperature, relative humidity,
specific humidity, potential temperature, winds and omega.Longitude by Height Chose latitudes to be averaged over and
longitude range to be shown. Note that humidity
variables only go through 300mb and omega only goes to
100mb.

The main interface for this page is an html form. The
data that are input into this form are processed by a Perl script.
The script reads the inputs, tests for bad inputs and then executes
a FORTRAN code that produces a composite file (in netCDF). This
file is what is processed by a GrADS script. The GrADS script is
run as a batch job. Plot options are input
into the GrADS script. The plot in the frame buffer is
converted to gif and this gif is displayed as part of a html
document. The netCDF file and the gif file are kept in a directory
where the files are periodically deleted.

Please let me know if find the page useful. Likewise,
let me know if you think any instructions are unclear, if you think
there are bugs or if you have any suggestions for improvements of
any type. I would particularly like to know if you use these pages
for teaching purposes and if so, how. I can be reached by email at
cathy.smith@noaa.gov or by phone
at (303) 497-6263.